Saturday, January 28, 2017

A Flagrant Exercise in Laziness Concerning Chalcidoids

After several years of deferrals, I finally got around this May to penning a post for the Ohio State University's Triplehorn Insect Collection. I'll take this opportunity to shamelessly self-plagiarize.

I have always been fascinated by insects, but it was not until, at
age 15, I took a week-long field insect taxonomy course at the Ohio State University’s Stone Laboratory.
There, I learned the conventions of arthropod collection and
preservation and something of proper curatorial practices. Ever since, I
have steadily accumulated a collection with pretensions made modest by
the limited resources of a teenager; and collection and identification
remain an exceedingly enjoyable activity for me.

Therefore, it was only natural that I gravitated to the Triplehorn
Insect Collection upon commencing my undergraduate career. Sorting
unidentified specimens was easily my favorite task there. Although the
collection contains the full range of insect diversity, those specimens
that I was tasked with identifying almost always belonged to the order
Hymenoptera—often casually referred to as “ants, bees, and wasps”, but
technically including far more taxa than simply those that happen to
have colloquial names.Being one of the four most diverse insect orders, the variety of
Hymenoptera is considerable: and I encountered much of their
phylogenetic span through this process, while becoming intimately
familiar with Goulet and Huber’s tome Hymenoptera of the World: an Identification Guide to Families (1993) (PDF),
the monochromatic line drawings within which—printed on thick, coarse
paper—have caused hymenopterists to nickname it “the coloring book”.

Paratype of Dicopomorpha echmepterygis, male(Huber & Noyes, 2013)

As an exemplar of the many taxa with which I thereby became familiar,
I have chosen to briefly discuss the superfamily Chalcidoidea herein.
These parasitoid wasps are one of those aforementioned many prominent insect taxa that have no
name in the vernacular—understandable, given that the vast majority of
these particular parasitoids are a few millimeters in length or less.
(Indeed, the smallest insect known to science—the 0.13-mm.-long male of Dicopomorpha echmepterygis [Mockford, 1997]—is a chalcidoid.)

This diminution has also resulted in a lack of taxonomic attention
from entomologists, and chalcidoid systematics is by consequence a
frustratingly opaque matter—something one is immediately impressed with
while attempting to identify the miniscule things: keys are peppered
with qualifiers like “usually” and “most”, not to mention annotated with
lengthy footnotes elucidating the exceptions to each couplet. The
fundamental problem at hand, as Goulet and Huber point out, is that
chalcidoid families are often defined by combinations of characters, as
opposed to singular traits that are unique to that taxa and none other (autapomorphies,
in cladistic terms). This has resulted in a superfamily littered with
taxa whose boundaries are under constant debate (e.g., the Agaonidae) or
that do not hold up to scrutiny whatsoever (the grossest wastebasket
taxon of flagrant wastebasket taxa, the Pteromalidae).

Chalcidoids are hardly deserving of this neglect, considering their
ecological and numerical diversity (they possibly constitute 10% of all
insect species; Noyes, 2003). I would have impartially respected this
significance regardless of my work at the Collection, but parsing
through unit tray after unit tray of nigh-microscopic specimens
representing untold numbers of species—each one a chalcidoid—gave me a
concrete grasp of that abstraction.

I still have strong visual impressions of many of them: the subtly
turquoise, spatula-shaped abdomen I swiftly came to associate with the
Tetracampidae; the minute serrations on the inner rims of a stocky
chalcidid’s femora, making its thighs appear like chitinous razors; the
oar-like forewings of many an insubstantial mymarid, fringed with haloes
of setae; the metallic, spindle-shaped abdomen that accounted for
two-thirds the length of a sycoryctine. I am not the only one to have
thought them often quite showy under sufficient magnification: Alexandre
A. Girault, a notoriously verbose chalcidologist, spoke of the tiny
wasps as “gem-like inhabitants of the woodlands, by most never seen or
dreamt of” (Thomer & Twidale, 2014).

Suffice it to say, without my work at the Collection, I would not have seen nor dreamt of so many chalcidoids.___________________________________________________________________Huber, J. T. and Noyes, J. S. (2013).A new genus and species of fairyfly,
Tinkerbella nana (Hymenoptera, Mymaridae), with comments on its sister genus
Kikiki, and discussion on small size limits in arthropods. Journal of Hymenoptera Research, 32, 17-44. Retrieved 1/6/17 from http://jhr.pensoft.net/articles.php?id=1635

Mockford, E. L. (1997). A new species of Dicopomorpha (Hymenoptera: Mymaridae) with diminutive, apterous males. Annals of the Entomological Society of America, 90, 115-120.